Helmet with slip plane system

ABSTRACT

A helmet may have an inner liner forming a body of the helmet, the inner liner having a concave inner surface defining a cavity configured for receiving a wearer&#39;s head. A plurality of slippage pads are disposed at selected locations on the concave inner surface and connected to the inner liner, the slippage pads having an elongated shape with a length and a width, the length being greater than the width, the slippage pads each defining a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer&#39;s head, the openings aligned longitudinally along the length of the slippage pads. A plurality of projecting cushioning pads are disposed adjacent to the slippage pads, and have a greater height than the slippage pads and exhibiting a greater deformability than the slippage pads.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority of U.S. patent application No. 63/219,539, filed on Jul. 8, 2021, and of U.S. patent application No. 63/220,741, filed on Jul. 12, 2021, and of U.S. patent application No. 63/249,059, filed on Sep. 28, 2021, the contents of all of which are incorporated herein by reference.

TECHNICAL FIELD

The present application relates to sport helmets, such as bicycle helmets.

BACKGROUND OF THE ART

Bicycle helmets have become ubiquitous for cycling activities, and other sports. In road and urban bicycle riding, one specific helmet construction is commonly used, that consisting of the foam inner liner with an outer shell. The inner liner forms the body of the helmet in terms of volume and structural integrity. The inner liner is typically made of a structural foam material such as expanded polystyrene. An outer shell covers the liner and defines the smooth, aerodynamic and/or decorative exposed outer surface of the helmet. The outer shell and liner may commonly be co-molded, and additional structural and attachment components may be present. Other components include the attachment system inside the outer shell, by which the helmet is secured to the user's head. The above-referred configuration is quite convenient in terms of providing suitable head protection, while being lightweight.

However, while protecting the head from some form of traumatic injuries such as skull fractures and skin wounds, helmets may leave the wearer exposed to some other forms of trauma, such as concussions. For example, angled impacts on one's head may result in a concussion, in spite of the presence of a helmet. Moreover, the liner is a stiff component that may be uncomfortable to a wearer. Accordingly, some technologies have been developed to assist in absorbing shocks, such as that described in U.S. Pat. No. 8,578,520. It describes the presence of an attachment device that accommodates the wearer's head. The attachment device is a low-friction layer that creates a relative motion between the inner liner and the skull, at a point of angled contact. Hence, rotational energy is directed away from the brain, so as to reduce the strain in the brain tissue at an impact.

SUMMARY

Therefore, it is an aim of the present disclosure to provide a helmet that addresses issues associated with the prior art.

In accordance with an aspect, there is provided a helmet comprising: at least an inner liner forming a body of the helmet, the inner liner having a concave inner surface defining a cavity configured for receiving a wearer's head; a plurality of slippage pads disposed at selected locations on the concave inner surface and connected to the inner liner, the slippage pads having an elongated shape with a length and a width, the length being greater than the width, the slippage pads each defining a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer's head, the openings aligned longitudinally along the length of the slippage pads; a plurality of projecting cushioning pads disposed adjacent to the slippage pads, and having a greater height than the slippage pads and exhibiting a greater deformability than the slippage pads; and an attachment system to attach the helmet to the wearer's head.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a helmet with a slip plane system in accordance with the present disclosure;

FIG. 2 is a perspective view of an inner cavity of the helmet of FIG. 1 showing a distribution of slippage pads and projecting cushioning pads, in accordance with the present disclosure;

FIG. 3 is a perspective view of the slippage pad as used in the helmet of FIGS. 1 and 2 ;

FIG. 4 is a top view of the slippage pad of FIG. 3 ;

FIG. 5 is an elevation view of the slippage pad of FIG. 3 ;

FIG. 6 is an elevation view of showing a side by side arrangement of a slippage pad and projecting cushioning pads;

FIG. 7 is a view of the slippage pad of FIG. 3 , with exemplary dimensions; and

FIG. 8 is a view of the projecting cushioning pad of FIG. 2 , with exemplary dimensions complementary to the exemplary dimensions of the slippage pad of FIG. 7 .

DETAILED DESCRIPTION

Referring to the drawings, and more particularly to FIGS. 1 and 2 , there is illustrated a helmet 10 in accordance with the present disclosure. The helmet 10 is of the type that is used for cycling and like sporting activities. For simplicity, an attachment system is only summarily shown as 11, with components left out for simplicity. The attachment system is typically anchored to an interior of the helmet and features straps for the helmet to be strapped to the user's head. The attachment system may also include rigid attachment components in the rear of the helmet (e.g., male and female bucket members), to adjust the helmet to a circumference of the wearer's head. Hence, although summarily shown, the helmet 10 has such attachment means of any appropriate form.

The helmet 10 has a generally hemispherical shape formed by an inner liner 12 and an outer shell 13. By its hemispherical shape, the helmet 10 has an inner concave surface and outer convex surface, with the top and side of the wearer's head being received in the inner concavity. The inner liner 12 is typically made of foam (e.g., expanded polystyrene or the like) and constitutes the major component of the helmet 10 in terms of volume and energy absorption capability: it is the structure of the helmet 10. Moreover, the foam is of the type being generally rigid and hence providing the structural integrity to the helmet 10, in terms of maintaining its shape. In other words, the foam liner is not of the resilient type that is supported by a rigid shell, but rather of the type that is the main structural component of the helmet 10. It is by the combination of the attachment system 11 and the inner liner 12 that the helmet 10 remains attached to the wearer's head. The inner liner 12 covers an upper portion of the head, and the attachment system 11 prevents the inner liner 12 from being pulled off (in translation). However, some play may be present between the head of the wearer and the inner liner 12, due to the somewhat complementary spherical shapes. The play may enable absorption of angled impacts on the helmet.

The outer shell 13 is integrally connected to the inner liner 12 and forms the major portion of the exposed convex surface of the helmet 10. The integral connection may be achieved by way of adhesives or co-molding (i.e., molding of the inner liner 12 with the outer shell 13 positioned in the mold cavity beforehand). The outer shell 13 is made of a plastic layer, such as polycarbonate or the like, as a possibility. The outer shell 13 defines the smooth and decorative outer surface of the helmet 10. Other components may be present, such as a cage, as described in U.S. patent application Ser. No. 14/049,375, the contents of which are incorporated herein by reference. Also, the helmet 10 may have an inner liner 12, but no other shell 13, or multiple shell segments, among other possible variants.

Referring to FIGS. 1 and 2 , vents 14 are shown as being defined at least partially by the inner liner 12, and allow air circulation in and out of the helmet 10. Cushioning pads 15 may be distributed at various locations in the interior of the helmet 10. A plurality of slippage pads 20 and of projecting cushioning pads 30 distributed in the inner cavity of the helmet 10, in a manner described below. The cushioning pads 15, the slippage pads 20 and the projecting cushioning pads 30 are padding interfaces between a surface of the inner cavity of the inner liner 12 and the wearer's head. The cushioning pads 15, slippage pads 20 and the projecting cushioning pads 30 serve no function of attachment of the helmet 10 to the wearer's head. The cushioning pads 15, the slippage pads 20 and/or the projecting cushioning pads 30 provide cushioning to make the helmet 10 more comfortable, and may hence reduce some of the play between the inner liner 12 and the wearer's head. The cushioning pads 15, the slippage pads 20 and/or the projecting cushioning pads 30 may also perform some management of the linear and rotational forces and movement that occur upon impact on the helmet 10.

Moreover, the slippage pads 20 may allow a relative slippage motion between the surface of the inner liner 12 and the head of the wearer, in quasi-translational manner. As the surface of the inner liner 12 is concave, it is not fully flat. Hence, the movement is not purely translational, but close to a translation, explaining the use of the expression quasi-translational, as well as the expression slip plane system, as non-flat planes of the inner liner 12 and of the skull of the wearer may move relative to one another. The movement may also be described as a sliding movement of a part of the slippage pads 20 relative to the concave surface of the inner liner 12. It is the resistance of this sliding movement that allows absorption of angled impacts on the helmet 10.

Referring to FIG. 3 , an embodiment of the slippage pad 20 is shown. The slippage pad 20 forms a series of tubes 21, interconnected to each other by a common wall 22. As shown, the slippage pad 20 has a pair of tubes 21 with their respective openings 21A made on their respective head contacting surface for being oriented towards the wearer's head when provided in the helmet 10 and when the helmet 10 is worn. The slippage pad 20 of FIGS. 3 to 5 has a generally rectangular outline, but other shapes are considered, such as oval. Stated differently, the slippage pad 20 has a sequence of openings 21A, in this case obround holes (though other shapes are contemplated, including rectangular, with or without rounded corners), defined therethrough, opened toward the wearer's head. The openings 21A may have the same size, or a different size. The openings 21A are spaced apart from each other by the common wall 22 in between them. In an embodiment, such as shown, the slippage pad 20 has two openings 21A adjacent to each other. In an embodiment, the slippage pad 20 has a single row of openings 21A. In other words, in an embodiment, the openings 21A are aligned in a single row extending along the length of the pad 20, shown as being along axis X). The dimensions of the slippage pads 20 may be any appropriate dimensions for use in a helmet 10. In an embodiment, the slippage pads 20 have an elongated shape with a length of 40 mm±20 mm (i.e., along axis X), and a width of 13 mm±7 mm (i.e., along axis Y). The slippage pads 20 may have other dimensions. A thickness of the slippage pads 20 may range between 2 mm and 10 mm (i.e., along axis Z). The slippage pads 20 may have other thickness dimensions in other embodiments. As shown, the slippage pads 20 all have the same dimensions and shape. However, this may be different in other embodiments, where at least some or all of the slippage pads 20 may be shaped and/or dimensions differently from one another.

The openings 21A may have an elongated shape with a length of 15 mm±5 mm and a width of 5 mm±3 mm. In the embodiment shown, the common wall 22 between the adjacent openings 21A has a minimum longitudinal dimension (dimension taken along the length of the pad 20, shown as being along axis X) of 4 mm±2 mm. In an embodiment, the minimum longitudinal dimension of the common wall 22 is between 10% to 20%, inclusively of the length of the slippage pad 20 of FIGS. 3-5 . Other dimensions may be contemplated for the openings 21A in other embodiments. The expression “minimum longitudinal dimension” is used considering that the wall 22 may not have a constant dimension, notably if the openings 21A are obround.

There may be more than two openings 21A per slippage pad 20 in other embodiments. The openings 21A may be evenly distributed in said slippage pad 20, although this may be different in other embodiments (non even distribution). The dimensions of the openings 21A may be defined as a ratio of their dimensions with a corresponding dimensions of the slippage pad 20. For instance, in an embodiment, a ratio of the sum of the length of the openings 21A over the length of the slippage pad 20 is 70%±20%. A ratio of the width of the openings 21A over the width of the slippage pad 20 may range between 25% and 40%—the width being along axis Y. Other ratios may be contemplated in other embodiments. As shown in FIG. 5 , the slippage pad 20 may optionally have a base 23, with its undersurface 24, as discussed above with respect to other embodiments. Stated differently, the openings 21 may be through openings, i.e., open on opposed sides of the slippage pad 20 of FIGS. 3-5 , but it is also contemplated to have the tubes 21 in a close-ended configuration, i.e., one end being closed, by way of the base 23. For example, the closed end could be the one against the inner liner 12, as this closed end could increase the bonding surface of the slippage pad 20 with the inner liner 12. The slippage pad 20 may be disposed at selected locations on the inner liner 12 of the helmet 10, as discussed above and shown in FIG. 2 . Also, such slippage pads 20 may be combined with cushioning pads 15 distributed in the inner cavity of the helmet 10, in an alternating sequence of slippage pads 20 and cushioning pads 15, or otherwise, for instance. According to an embodiment, the slippage pad 20 of FIGS. 3-5 is monoblock. The base 23, if present, may or may not be part of the monoblock.

The slippage pad 20 of FIGS. 3 to 5 may be integrally molded into a resilient elastomer, such as a monoblock piece of a single material. The material is selected to be compliant and have flexibility, i.e., be capable of movements in the elastic deformation range, to then regain the native shape of FIGS. 3 to 5 . The slippage pads 20 may be made of a composite material including polyurethane (PU) and a non-Newtonian polymeric material, such as the DCLAN™ gel discussed above, the D3O™ material, or another non-Newtonian material. In an embodiment, a density of such slippage pads 20 is 0.27 g/cm³±0.10 g/cm³. Other densities may be contemplated in other embodiments. The slippage pads 20 may be formed as an integral monolithic piece of a non-Newtonian polymeric material in other embodiments. Other materials, of non-Newtonian or Newtonian types may be contemplated in other embodiments. For instance, in other embodiments, the slippage pads 20 may be made of a polymeric material, such as silicone, polyethylene (PE), polypropylene (PP), thermoplastic polyurethane (TPU), rubber, with or without the addition of a non-Newtonian polymeric material. As discussed above, the non-Newtonian polymeric material may provide great energy absorption characteristics because of its rheological behaviour when subjected to an impact, as it may harden from a non-rigid state (i.e. a gel state) to form an impact protection layer while absorbing, at least partially, the impact energy. This may provide improved impact energy absorption when subjected to a low density energy impact and/or a high density energy impact, as the non-Newtonian polymer may rheologically respond differently to low impact energy and to high impact energy.

A bottom portion of the slippage pad 20 may be received in a recess defined within the inner liner 12. At least part of the bottom portion of the slippage pad 20 may be adhesively bonded to the inner liner 12 or cushioning pad 15. For instance, bonding zones are located at the bottommost portion of the slippage pad 20 only. This may allow the remainder of the bottom portion of the slippage pad 20—i.e., one that is unattached to the inner liner 12—just as the top portion of the slippage pad 20, to deform “laterally”, stretch, buckle, distort, and/or shear when an angled impact (e.g. angled force or tangential force relative to a longitudinal axis of the slippage pad 20) is made on the helmet 10, even though the bottom portion may be in a recess and surrounded by the material of the inner liner 12. In other words, the peripheral surface of the bottom portion, where it is not adhesively bonded or physically attached to the liner 12, may move toward and away from the recess wall when the slippage pad 20 deforms. Other ways for securing the slippage pads 20 to the inner liner 12 or cushioning pad 15 may also be contemplated, such as mechanical interlock due to interlocking shapes of the slippage pads 20 and a recess, for instance.

The slippage pads 20 may be described as having an elongated shape with a length and a width, the length being greater than the width, the slippage pads 20 each defining a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer's head, the openings aligned longitudinally along the length of the slippage pads. In a variant, the slippage pads 20 may also be described as defining blocks of resilient material, the blocks having an elongated shape with a length and a width, the length being greater than the width, the blocks each having a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer's head, the openings aligned longitudinally along the length of the blocks, the openings being empty. In a variant, the slippage pads 20 may be described as defining blocks of resilient material, the blocks being monoblock pieces made of a single material, the blocks having an elongated shape with a length and a width, the length being greater than the width, the blocks each having a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer's head, the openings aligned longitudinally along the length of the blocks.

Referring to FIGS. 2 and 6 , the projecting cushioning pads 30 are shown in the helmet 10, as projecting from head-facing surface of the inner liner 12. The projecting cushioning pads 30 are used in combination with the slippage pads 20 for the added safety and comfort of the helmet 10 on the wearer. In an embodiment, the projecting cushioning pads 30 are aligned with a length of the slippage pads 20. For example, one of the projecting cushioning pads 30 is at each longitudinal end of the slippage pad 20, as shown by direction X in FIG. 6 . Therefore, one set of pads 20 and 30 may include two of the cushioning pads 30 for one slippage pad 20, with the slippage pad 20 between the cushioning pads 30, as shown in FIG. 6 . Other arrangements are considered, such as one for one, a sequence of two pads 30, one pad 20, one or two pads 30. Moreover, while the pads 30 are shown are longitudinal ends of the pad 20, they may also be positioned width wise (direction Y).

As observed from FIG. 6 , the height of the cushioning pads 30 is greater than the height of the slippage pads 20, the height being along direction Y. In an embodiment, the height of the cushioning pad 30 is between 5% and 40% greater than the height of the slippage pad 20, and/or 2-3 mm higher than the slippage pads 20. In an embodiment, the height of the cushioning pads is 7 mm in an uncompressed condition, but may be between 2.1 mm and 14 mm. When the cushioning pads 30 are positioned side by side with the slippage pads 20, the height of the cushioning pads 30 is such that they project beyond an exposed head-contacting surface of the slippage pads 20. Therefore, when the helmet 10 is installed on a user's head, the head will contact the cushioning pads 30 prior to contacting the slippage pads 20. A gap may be present between the slippage pads 20 and the cushioning pads 30, as shown. Cushioning pad 15 may or may not be present in the gaps.

In a variant, a deformability of the cushioning pads 30 is greater than that of the slippage pads 20. More specifically, the cushioning pads 30 may exhibit lesser resistance to compression than the slippage pad 20. In another embodiment, in spite of a compression due to the contact with the head, the height of the cushioning pad 30 may remain greater than that of the slippage pad 20. The cushioning pads 30 are typically made of a closed cell foam, such as expanded polypropylene or polyethylene. Open cell foams may also be used. The cushioning pads 30 may also be made of a combination or materials, with a fabric or felt for the interface with the cranium. In an embodiment, the cushioning pad 15 has greater flexibility than the cushioning pads 30. An exemplary hardness for the cushioning pads 30 is of 10 for a type A durometer.

The cushioning pads 30 may have different shapes. In the embodiment of FIG. 2 , the cushioning pads 30 are cylindrical in shape and sit on one of their circular end faces, and hence may be described as being cylindrical tubes, or even upstanding cylindrical tubes. In another embodiment, the cushioning pads 30 may be described as being solid, i.e., not hollow, solid here not intended to refer to rigidity. Therefore, in the case of linear impacts, it may be the cushioning pads 30 that elastically deform to lessen the impact on the cranium of the user. In the case of rotational impacts, the slippage pads 20 would enable the slippage deformation as described above. The cushioning pads 30 may have a largest cross-section dimension (e.g., diameter) of at least 10 mm, and a height ranging between 3 mm and 14 mm, while also being higher than the slippage pads 20 in a native or rest condition. As observed from FIG. 6 , the cushioning pads 30 may be hollow and possibly tubular.

The cushioning pads 30 may be removably connected to the inner liner 12, such as, by Velcro™. The cushioning pads 30 may also be connected in other ways or in supplemental ways to the helmet 10 in other embodiments, such as by adhesive bonding or other means for permanently and/or releasably connecting the cushioning pads 30 to the inner liner 12.

In operation, when an angled impact is made on the helmet 10, depending on the magnitude of an impact, the slippage pads 20, in contact with various discrete locations of the wearer's head, allow displacement of the inner liner 12 relative to the wearer's head, by deformation of the slippage pads 20, while the slippage pads 20 remain bonded to the inner liner 12. While the slippage pads 20 are deforming, for instance “laterally”, the slippage pads 20 may compress to absorb energy from the angled impact. In case of a linear impact, the cushioning pads 30 may compress until the cranium contacts the slippage pads 20. This is permissible due to the greater height of the cushioning pads 30 than that of the slippage pads 20. Accordingly, a dual reaction is permissible, based on the nature of the impact.

In another variant of operation, when an angled impact is made on the helmet 10, again depending on the magnitude of an impact, the cushioning pads 30 may first compress until the cranium contacts the slippage pads 20. Then, the slippage pads 20, in contact with various discrete locations of the wearer's head, further allow displacement of the inner liner 12 relative to the wearer's head, by deformation of the slippage pads 20, while the slippage pads 20 remain bonded to the inner liner 12. This sequence is permissible due to the greater height of the cushioning pads 30 than that of the slippage pads 20.

If a recess wall is present, a gap may be created between a recess wall and the peripheral surface of the bottom portion of the slippage pad 20. Thus, at least part of the peripheral surface of the bottom portion moves away from the recess wall while an opposite part of the peripheral surface of the bottom portion is compressed against the recess wall as a result of the deformation of the slippage pad 20. The bottom portion of the slippage pad 20 may have a size and shape corresponding to the shape and size of the recess in which it is received, this may be different in other embodiments. For instance, the recess may be larger than the bottom portion of the slippage pad 20, such that only the bottommost portion of the slippage pad 20 that is secured to the inner liner 12 contacts the recess wall, when the slippage pad 20 is in an non-deformed state. This may allow the bottom portion to expand laterally when the slippage pad 20 is compressed longitudinally, which may increase the amount of energy absorption due to angled impact, for instance. In other cases, the recess may be smaller than the bottom portion of the slippage pad 20, such that the bottom portion does not entirely recede within the recess.

Referring to FIG. 2 , there is shown an inner cavity of the helmet 10 having a number of slippage pads 20 of the type shown in FIGS. 3 to 5 , disposed at selected locations on the inner liner 12 of the helmet 10, with cushioning pads 30 adjacent to the slippage pads 20, in a manner replicating the arrangement of FIG. 6 , i.e., two cushioning pads 30 for one slippage pad 20. Other arrangements are also possible, such as a 1:1 ratio, or 1:2 ratio, etc. It is also contemplated to have different ratios at different regions of the helmet 10. There are also shown cushioning pads 15 disposed on the inner liner 12. The cushioning pads 15 are removably connected to the inner liner 12, such as, by Velcro™. The cushioning pads 15 may also be connected in other ways or in supplemental ways to the helmet 10 in other embodiments, such as by adhesive bonding or other means for permanently and/or releasably connecting the cushioning pads 15 to the inner liner 12. As shown, the cushioning pads 15 may define apertures that correspond in shape and dimensions to the slippage pads 20 and/or projecting cushioning pads 30, for the slippage pads 20 and/or the projecting cushioning pads 30 to be surrounded by the cushioning pads 15, if desired. In such arrangement, there may or may not be direct connection between the cushioning pads 15 and the slippage pads 20. Some or all of the slippage pads 20 may be disposed within the apertures of the cushioning pads 15, though this is optional. The cushioning pads 15 may thus contour at least some of the slippage pads 20. This may improve comfort of the helmet 10 having such slippage pads 20, as the cushioning pads 15 and the slippage pads 20 may form a continuous head contacting surface that contacts the wearer's head when the helmet 10 is worn. The cushioning pads 15 may not have such apertures in other embodiments, for instance, where the cushioning pads 15 and the slippage pads 20 are distributed in an alternating sequence of slippage pads 20 and cushioning pads 15, or otherwise, as discussed above. The helmet 10 may be without cushioning pads 15 altogether.

As shown, the slippage pads 20 and projecting cushioning pads 30 are connected to the inner liner 12. The slippage pads 20 and projecting cushioning pads 30 may be connected to the inner liner 12 by adhesive bonding. Other ways to secure the slippage pads 20 to the inner liner 12 may be contemplated in other embodiments, such as co-molding, mechanical interlocking or via mechanical connectors, such as mechanical fasteners. As shown, the slippage pads 20 and projecting cushioning pads 30 are directly connected to the inner liner 12. In other embodiments, the slippage pads 20 may be connected to an intermediary piece of material, such as a web, or a layer of material such as a layer of woven material, interconnecting the slippage pads 20 and projecting cushioning pads 30 together. This may facilitate handling of the slippage pads 20 and projecting cushioning pads 30 as a cluster of slippage pads 20 and projecting cushioning pads 30 during manufacturing and/or assembly of the helmet 10, amongst other things.

In an embodiment, the slippage pads 20 have a base portion Z1 along axis Z (FIG. 3 ) received in respective recesses defined within the inner liner 12, with a head contacting portion Z2 projecting beyond a plane of the inner liner 12. The recesses, if present, and the slippage pads 20 may be dimensioned to be in a close fit fashion, which may allow the slippage pads 20 to be “laterally” retained on the inner liner 12. This may help securing the slippage pads 20 to the inner liner 12 and/or provide a mechanical abutment between the slippage pads 20 and the inner liner 12, thereby reducing the shear stress in the adhesive bonding that may connect the slippage pads 20 to the inner liner 12, in embodiments where such adhesive bonding is present, during shear deformation of the slippage pads 20.

The slippage pad 20 has the head contacting portion Z2 that protrudes from the concave inner surface of the inner liner 12, out from the recess if present. The recesses may allow the slippage pads 20 to have a greater overall thickness, which may increase the energy absorption of the slippage pads 20, as opposed to embodiments where the inner liner 12 has no recess receiving the slippage pads 20. The recesses may thus allow the use of thicker slippage pads 20 while concurrently keeping the helmet 10 “compact”, in that the inner liner 12 may still remain close to the wearer's head when the helmet 10 is worn. This may contribute to having a helmet 10 that appears less bulky on the wearer's head without compromising on the thickness of the slippage pads 20 between the wearer's head and the inner liner 12. In embodiments where the recesses are present, a ratio of a recess depth over the thickness of the slippage pads 20 is no more than 1:2, (i.e., dimension of Z1 along axis Z over Z1+Z2). In some cases, such ratio may be no more than 1:3, and in some cases no more than 1:4. Other ratios are possible in other embodiments.

An angled impact on the helmet 10 having such slippage pads 20 projecting cushioning pads 30 may result in geometrical deformation of the tubes 21 relative to the wearer's head. In other words, an angled impact on the helmet 10 may result in a movement resulting from deformation of the tubes 21 and of the projecting cushioning pads 30, and relative movement of the head contacting surface of the slippage pads 20 with respect to the inner liner 12. Some or all of the slippage pads 20 and projecting cushioning pads 30 may be subjected to local deformation independently of how the other slippage pads 20 and projecting cushioning pads 30 react. The common reaction of the slippage pads 20, which may correspond to the sum of deformations of the slippage pads 20 disposed at selected locations on the inner liner 12 of the helmet 10, when an angled impact on the helmet 10 is made, may provide impact energy absorption via geometrical deformation of the slippage pads 20. As such, the amount of impact energy transmitted to the wearer's head may be less than that transmitted to the wearer's head when the slippage pads 20 are absent from the helmet 10, in some embodiments. The deformation of the slippage pads 20, as mentioned previously, may be in the form of flexion, compression, distortion, shearing and/or buckling of the tubes 21.

The helmet 10 defines a frontal portion for covering at least partially a frontal region of the wearer's head, a rear portion for covering a rear region of the head, opposite lateral portions for covering opposite lateral regions of the head, and a top portion for covering a top region of the head. With continued reference to FIG. 2 , a number of slippage pads 20 and of projecting cushioning pads 30 may be disposed at selected locations within the cavity of the helmet 10, between the inner liner 12 and the wearer's head when the helmet 10 is worn, to contact respective portions of the wearer's head. There may be at least two slippage pads 20 and/or projecting cushioning pads 30 in each of the frontal, rear, and top portions of the helmet 10 to locally contact the wearer's head, and at least one slippage pad 20 and/or projecting cushioning pads 30 in each of the opposed lateral portions of the helmet 10. In an embodiment, such as shown, at least two slippage pads 20 and/or projecting cushioning pads 30 are longitudinally disposed on each side of a sagittal plane X-X of the helmet 10 (FIG. 2 ), which bisects the inner cavity into opposite inner cavity lateral regions. The slippage pads 20 and/or projecting cushioning pads 30 on each side of the sagittal plane X-X, located respectively in the frontal and top portions of the helmet 10, may be longitudinally oriented transversally (transversally or in some cases perpendicularly) to a frontal plane Y-Y (FIG. 2 ) of the helmet 10, which bisects the inner cavity of the helmet 10 in respective rear and frontal inner cavity regions. That is, the at least two slippage pads 20 and/or projecting cushioning pads 30 may be longitudinally oriented in a front-to-rear direction of the helmet 10, their respective longitudinal projections extending between the opposite lateral portions of the helmet 10. In this disposition, the footprint of the slippage pads 20 may be generally longitudinally aligned with a force vector resulting from an angled impact oriented toward the frontal portion of the helmet 10. The force vector of the angled impact may have a linear component, which may be generally transverse to the convex outer surface of the helmet 10, that may induce compression deformation in the slippage pads 20 located in the front portion of the helmet 10. The force vector of the angled impact may also have a tangential component, which is tangent to the convex outer surface of the helmet 10 and aligned in a front-to-rear direction of the helmet 10, whereby the slippage pads 20 are induced with shearing deformation along the longitudinal dimension of their footprint. This may provide better friction/adherence of the head contacting surface of the slippage pads 20 with the wearer's head to cause the shearing deformation and/or allow a better transmission of the impact energy from the outer shell 13 to the slippage pads 20 in compression and/or shear to absorb the impact energy, at least partially, for instance.

Additionally, the at least one slippage pad 20 in the opposite lateral portions of the helmet 10 are located on the inner liner 12 at locations that intersect with the frontal plane Y-Y of the helmet 10. The at least two slippage pads 20 located in the rear portion of the helmet 10 are longitudinally oriented such that their respective longitudinal projections are transverse to the longitudinal projections of the slippage pads 20 of the frontal and top portions of the helmet 10. The individual position of the slippage pads 20 and their relative positions may be different in other embodiments.

Referring to FIGS. 7 and 8 , exemplary dimensions of the slippage pad 20 and of the projecting cushioning pad 30 are provided, these exemplary dimensions corresponding in proportions for a set of slippage pad 20/projecting cushioning pad 30. Stated differently, when the helmet 10 has slippage pads 20 with projecting cushioning pads 30 having the dimensions set out in FIGS. 7 and 8 , the helmet 10 may react in the manner described herein when subjected to lateral impacts. Other dimensions than those shown may be used, the values of FIGS. 7 and 8 merely being provided as examples.

In FIG. 7 , the slippage pad 20 is shown having a length of 40.5 mm, a width of 13.0 mm. The width of the openings 21A is 5.0 mm, and a distance between the same ends of the openings 21A, in a lengthwise direction, is of 20 mm. A thickness (i.e., along Z) of the slippage pad 20 is of 5.0 mm±2.0 mm. The slippage pad 20 may have a hardness ranging from Duro 25-35 HC (as an example), and a density of 0.35 g/cm³. These values may alternatively vary by up to 20%. In FIG. 8 , the projecting cushioning pad 30 has an outside diameter (or largest sectional dimension) of 12.5 mm±2.5 mm. The projecting cushioning pad 30 may be hollow and have an inside diameter of 5.0 mm. A thickness (i.e., along Z) of the cushioning pad 30 may be of 7.0 mm±2.0 mm. These values may alternatively vary by up to 20%. However, in an embodiment, the cushioning pad 30 has a greater thickness than that of the slippage pad 20. A thickness ratio (i.e. along Z) of the cushioning pad 30 relative to the slippage pad 20 may be between 1.2 and 1.7, inclusively. The cushioning pad 30 may have a hardness ranging from Duro 12-18 HC (as an example), and a density differing from that of the slippage pad 20. 

1. A helmet comprising: at least an inner liner forming a body of the helmet, the inner liner having a concave inner surface defining a cavity configured for receiving a wearer's head; a plurality of slippage pads disposed at selected locations on the concave inner surface and connected to the inner liner, the slippage pads having an elongated shape with a length and a width, the length being greater than the width, the slippage pads each defining a number of integrally connected side-by-side tubes each having an opening adapted to be oriented toward the wearer's head, the openings aligned longitudinally along the length of the slippage pads; a plurality of projecting cushioning pads disposed adjacent to the slippage pads, and having a greater height than the slippage pads and exhibiting a greater deformability than the slippage pads; and an attachment system to attach the helmet to the wearer's head.
 2. The helmet as defined in claim 1, wherein all the slippage pads are shaped and size to be identical to each other.
 3. The helmet as defined in claim 1, wherein lateral pairs of the slippage pads are disposed on each side of a sagittal plane of the helmet.
 4. The helmet as defined in claim 3, wherein the lateral pairs of the slippage pads are evenly laterally spaced apart from the sagittal plane of the helmet.
 5. The helmet as defined in claim 1, wherein a frontal pair of the slippage pads is disposed in a frontal portion of the helmet.
 6. The helmet as defined in claim 1, further comprising at least one cushioning pad disposed on the concave inner surface of the inner liner.
 7. The helmet as defined in claim 6, wherein the cushioning pad has apertures defined therethrough, the apertures corresponding in shape and dimensions to the slippage pads, wherein some of the slippage pads and/or of the plurality of projecting cushioning pads are disposed within the apertures of the cushioning pad.
 8. The helmet as defined in claim 1, wherein the slippage pads have a length of 40 mm±20 mm, and a width of 13 mm±7 mm.
 9. The helmet as defined in claim 1, wherein the projecting cushioning pads have a largest sectional dimension of 12.5 mm±2.5 mm.
 10. The helmet as defined in claim 1, wherein the projecting cushioning pads have a height of 7.0 mm±2.0 mm.
 11. The helmet as defined in claim 10, wherein the slippage pads have a height of 5.0 mm±2.0 mm.
 13. The helmet as defined in claim 1, wherein a density of the slippage pads is 0.27 g/cm³±0.10 g/cm³.
 14. The helmet as defined in claim 1, wherein the slippage pads are made of a composite material including polyurethane and a non-Newtonian polymeric material.
 15. The helmet as defined in claim 1, wherein the plurality of tubes is a pair of tubes, the openings of the pair of tubes each having an obround shape.
 16. The helmet according to claim 1, wherein the projecting cushioning pads have a height that is between 5% and 40% greater than that of the slippage pads.
 17. The helmet according to claim 1, wherein the projecting cushioning pads are cylindrical tubes.
 18. The helmet according to claim 1, wherein the projecting cushioning pads have a hardness ranging from Duro 12-18 HC.
 19. The helmet according to claim 1, wherein the slippage pad have a hardness ranging from Duro 25-35 HC.
 20. The helmet according to claim 1, wherein a thickness ratio of the projecting cushioning pad relative to the slippage pads is between 1.2 and 1.7, inclusively. 